1. Field of the Invention
This invention relates to an interrupt handling technique of an information processing apparatus such as a personal computer.
2. Background Art
In recent years, various types of personal computers such as a desktop personal computer and a notebook personal computer have come into widespread use. In this kid of personal computer, various programs are executed in sequence for each predetermined processing unit; interrupt management is conducted to interrupt the processing being executed and execute processing with higher priority. SMI (system management interrupt) is available as one interrupt management.
The SMI is an interrupt for causing BIOS (basic input/output system) to perform system proper processing (SMI processing) when a predetermined event (SMI event) occurs in the system; the SMI is started as an SMI signal is supplied to a CPU. (For example, refer to U.S. Pat. No. 6,446,153).
Accordingly, it is made possible to perform flexible operation control in such a manner that the processing mode is instantly switched from usual processing of an application program to special processing of the system in response to pressing a function key on a keyboard, for example.
By the way, recently it has been a common practice to install an SMI signal line for supplying an SMI signal to a CPU in a controller for interconnecting system buses (south bridge (SB)) because the controller is provided with a timeout notification function, etc., and the timeout is defined as an SMI event. Therefore, a notification of SMI event occurrence from an embedded controller (EC) is transmitted via the controller to the CPU.
On the other hand, recently the embedded controller has been a multifunctional device having both a power supply controller function and a keyboard controller function, for example, and each function can become the cause of an SMI. Accordingly, it becomes necessary for a BIOS processing section of BIOS operated when an SMI signal is supplied to the CPU to not only access the south bridge, but also access the embedded controller to determine the SMI cause. The reason is that the south bridge cannot determine the SMI event associated with which function has occurred although the south bridge can determine that a notification is received from the embedded controller. However, the embedded controller is connected to a low-speed system bus at a comparatively low stage with respect to the system and thus the responsivity of SMI processing performed by the BIOS is degraded.